I was under the same impression...but I believe, it is also connected to the joining of north and south American changing the ocean flow.....
Ok, so why is the article even talking about “the” ice age...as if there were only one?
http://en.wikipedia.org/wiki/Ice_age
Most interestingly, the Wikipedia article on Ice Ages also has a new piece of information that seems to parallel a hunch I've had for a long time: "According to research published in Nature Geoscience, human emissions of carbon dioxide will defer the next ice age. Researchers used data on the Earth's orbit to find the historical warm interglacial period that looks most like the current one and from this have predicted that the next ice age would usually begin within 1,500 years. They go on to say that emissions have been so high that it will not."
Recall that the last Ice Age glacial period nearly terminated mankind, and it's unlikely that (from a % surviving standpoint) we would do much better next time. A few extra degrees, IF they happen, is a much more survivable scenario. Also note from the graphs above that our current interglacial temperatures have not exceeded those of the last, nor are temperatures in the present period close to those in periods when life on earth was at it most prolific.